Download presentation
Presentation is loading. Please wait.
1
CELL TRANSPORT
2
Every living cell exists in a liquid environment.
One of the most important functions of the cell membrane is to keep the cell’s internal conditions relatively constant. Tomato plant must take in nutrients from the soil. Nitrogen Phosphorus Potassium
3
IN OUT What structure in the cell regulates
what substances enter the cell? The cell membrane regulates and controls which substances enter and leave the cell. IN Food Glucose O2 H2O OUT Waste Hormone CO2 H2O
4
There are two basic methods by which substances enter/exit the cell:
There are two basic methods by which substances enter/exit the cell: (1) Passive transport --- no energy needed (2) Active transport --- requires energy
5
Passive transport is the movement of substances across a cell membrane from an area of higher concentration to an area of lower concentration (requires no energy ) sugar Higher Concentration O2 salt aa Lower Concentration
7
Passive transport is the movement of substances across a cell membrane from an area of higher concentration to an area of lower concentration. NO ENERGY NEEDED sugar Higher Concentration O2 salt aa Lower Concentration
8
Small nonpolar substances such as CO2, O2, and small lipids can pass through the cell membrane by diffusion. Outside Cell CO2 O2 lipids InsideCell
9
Diffusion is the movement of substances from a region of higher concentration to a region of lower concentration. higher conc lower conc Low Conc Low Conc High Conc Low Conc
10
Even when the concentration of a substance is equal throughout a region, the molecules continue to move randomly.
11
Which way will fat move? That’s diffusion! LOW HIGH fat fat fat
inside cell fat fat fat LOW HIGH fat fat outside cell fat fat fat fat fat fat fat fat fat
12
Proteins in the cell membrane create
channels making it easy for certain molecules to pass. passive transport No energy needed glucose glucose higher conc lower conc Channel Proteins
13
Osmosis Water is very important, so we talk about water separately.
Cell survival depends on balancing water uptake & loss.
14
Osmosis is the movement of water across a cell membrane from a region of higher conc to a region of lower conc. Osmosis is the diffusion of water across a cell membrane. membrane Cell high conc H2O low conc H2O
15
How does water move? Always from an area of higher concentration
to an area of lower concentration. membrane Cell high conc H2O low conc H2O
16
The direction of osmosis depends on the relative concentration of solutes on the two sides of the membrane. low conc solute more water high conc solute Less water solute
17
How does water move? more water less water low conc solute more water
high conc solute Less water solute more water less water
18
Cells are always surrounded by some kind of solution
Cells are always surrounded by some kind of solution The solution surrounding cells may be: (1) isotonic (2) hypotonic (3) hypertonic
19
An isotonic solution has the same concentration of solute molecules as the cell.
Water moves in and out at the same rate Same conc of solutes outside the cell as inside the cell. 10 % solute 10 % solute
20
Example of isotonic condition
Your blood cells are surrounded by a watery solution called plasma. The concentration of solutes like sugars and minerals in plasma are the same as the concentration of solutes inside your blood cells.
21
IV fluid is not pure water, but rather a solution of electrolytes/minerals.
22
isotonic solution Same concentration inside the cell as outside the cell 2 % salt 2 % salt
23
isotonic solution 5 % glucose 5 % glucose
24
What happens if you place a red blood cell in pure water?
25
Less solute = more water
Sometimes the solution surrounding cells has a lower concentration of solutes than the cell. Less solute = more water 10 % solute more water 25 % solute less water
26
This means the concentration of water is greater outside the cell than inside.
10 % solute Water will move into the cell more water The cell will swell. 25 % solute less water
27
1 % salt 5 % salt
28
Pure water 2 % glucose
29
What happens if you place red blood cells in pure water?
The blood cells will take in water and the blood cells will swell and burst.
30
more solute = less water
Sometimes the solution surrounding cells has a higher concentration of solutes than the cell. more solute = less water 25 % solute less water 5 % solute more water
31
more solute = less water
Sometimes the solution surrounding cells has a higher concentration of solutes than the cell. more solute = less water 25 % solute Water will move out of the cell less water The cell will shrivel. 5 % solute more water
32
hypertonic solution 5 % salt 2 % salt
33
hypertonic solution 3 % glucose 1 % glucose
34
What happens if you place red blood cells in very salty water?
shriveled Water will move out of blood cells and the cells will shrivel.
36
ACTIVE TRANSPORT
37
In many cases, cells must move materials from an area of lower concentration to an area of higher concentration. Higher conc Lower conc
38
Active transport requires energy, in the form of ATP.
Active transport the movement of substances through a membrane from a region of lower conc to a region of higher conc. Lower Higher Active transport requires energy, in the form of ATP. requires ENERGY Lower conc glucose Higher conc glucose
39
Active transport uses transport proteins powered by chemical energy.
ATP Transport Protein
40
Some substances, such as macromolecules, are too large to pass through the cell membrane by regular transport. These substances are moved across the cell membrane by vesicles. I’m too BIG Vesicle
41
Endocytosis and exocytosis are transport mechanisms that transport large substances . Endocytosis and exocytosis require energy so they are types of active transport. Exocytosis ATP Endocytosis
42
Example (1): Some white blood cells called macrophages engulf and destroy bacteria by endocytosis.
43
Example (2): Some unicellular organisms, such as amoebas, take in food by endocytosis.
Similar presentations
